The invention begins with the current state of the technology as described, for example, in DE-OS No. 24 37 600. There the basic problem, that the eluant has such a high conductivity that measuring the conductivity of the ion species separated in the chromatography column is impossible, is solved by connecting to the latter a suppressor column of opposite ion exchange type as to the chromatography column. In the suppressor column the ion species passing the ions to be determined are exchanged for OH.sup.- or H.sup.+ ions. The disadvantage of this system is that the suppressor column can not be run continuously as the column must be periodically regenerated. In addition, the effect of the suppressor column varies with use and is dependent on chemical properties such as pH, diffusions, adsorption and exchange effects, all of which will reduce the reproducibility and exactness of the analyses.